CVE-2016-15042 in Frontend File Manager Plugin
Summary
by MITRE • 10/16/2024
The Frontend File Manager (versions < 4.0), N-Media Post Front-end Form (versions < 1.1) plugins for WordPress are vulnerable to arbitrary file uploads due to missing file type validation via the `nm_filemanager_upload_file` and `nm_postfront_upload_file` AJAX actions. This makes it possible for unauthenticated attackers to upload arbitrary files on the affected sites server which may make remote code execution possible.
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Analysis
by VulDB Data Team • 10/31/2024
The vulnerability identified as CVE-2016-15042 affects two WordPress plugins that were widely used for extending frontend functionality. The Frontend File Manager plugin version 4.0 and earlier, along with the N-Media Post Front-end Form plugin version 1.1 and earlier, contain critical security flaws that permit unauthenticated attackers to bypass file validation mechanisms. These plugins were designed to enable users to upload files through frontend interfaces, but they failed to implement proper input sanitization and validation checks. The vulnerability specifically resides in the AJAX handling mechanisms that process file uploads through the `nm_filemanager_upload_file` and `nm_postfront_upload_file` endpoints, which lack adequate file type verification. This flaw allows attackers to upload malicious files without authentication, creating a significant security risk for WordPress installations that utilize these plugins.
The technical implementation of this vulnerability stems from the absence of proper file type validation within the plugin code. When users attempt to upload files through the frontend interfaces, the plugins do not adequately verify the MIME types or file extensions of uploaded content. This missing validation occurs at the application layer where the AJAX handlers process the file uploads without proper sanitization. The vulnerability aligns with CWE-434, which describes insecure file upload vulnerabilities where applications accept files without proper validation of their content or type. Attackers can exploit this by crafting malicious files with extensions that bypass the plugin's limited validation logic, often using techniques such as double extensions or by exploiting the way different web servers handle file type detection. The lack of authentication requirements for these AJAX endpoints means that any visitor to the website can initiate file upload requests without needing valid credentials.
The operational impact of this vulnerability extends beyond simple unauthorized file uploads, as it creates potential for remote code execution on affected servers. When attackers successfully upload malicious files, they can leverage the server's file processing capabilities to execute arbitrary code, potentially leading to full system compromise. The vulnerability is particularly dangerous because it affects the frontend upload mechanisms that are often used by legitimate users for legitimate purposes, making it difficult to distinguish between normal usage and malicious activity. This creates a significant risk for WordPress sites that rely on these plugins for user-generated content management, as the attack surface expands to include any user who can access the frontend upload functionality. The vulnerability also enables attackers to potentially establish persistent backdoors, deface websites, or use the compromised servers for further attacks against other systems.
Organizations affected by this vulnerability should immediately implement multiple mitigation strategies to protect their WordPress installations. The primary recommendation involves upgrading to the latest versions of both plugins where security patches have been implemented, as the vendors have addressed this specific flaw in subsequent releases. Additionally, administrators should consider implementing web application firewalls that can detect and block suspicious file upload patterns, particularly targeting the specific AJAX endpoints mentioned in the vulnerability. Network-level protections should include monitoring for unusual file upload activities and implementing strict file type restrictions at the server level. The mitigation strategy should also incorporate regular security audits of installed plugins, ensuring that only trusted and up-to-date plugins are active on the system. According to ATT&CK framework, this vulnerability maps to T1190 - Exploit Public-Facing Application, and T1059 - Command and Scripting Interpreter, as it allows for both application exploitation and potential remote code execution. Organizations should also consider implementing principle of least privilege for file upload directories, ensuring that uploaded files have minimal permissions and are stored in locations that cannot be directly executed as web content.